Time Travel: Become the Only Master of Spells at the Beginning

[Special setting does not mean invincibility at the beginning] [Fast pace] [Multiple fights] [Original] "Will you die if I don't help you take revenge?..." "Shall I make a deal with you? You do something for me and I will tell you who killed your entire clan." "There's another... Secret about this world." A dying boy was "summoned" and traveled to a different world, where he was hosted by a female spirit. Only by helping her take revenge can she survive and return to her original world. He wanted to complete his revenge quickly, but he accidentally learned the truth about the world. Then he was involved in a bigger storm about "god"...